Posed of samuel t



S. T. SKEEN DRILL Filed Oct. 6, 1924 m x MW F b. as, 1929.

UNITED STATES P'lfENT QFFICE.

SAMIUEL T. SKEEN, OF CENTRALIA, ILLINOIS, ASSIG-INOR, BY DIRECT AND MESNE ASSIGNMENTS, TO THE S. & S. MANUFACTURING COMPAfl-lY, A PABTNERSHIP COM- POSED 0F SAMUEL T. SKEEN AND CHARLES E. STEAD.

DRILL.

Apphcation filed October 6, 1924. Serial No. 741,880.

This invention relates to a drill particularly adapted for use in drilling into coal deposits, one of the objects being to provide a very simple and inexpensive niiners drill having a blade, or hit, which may be easily detached from the drill stem with which it is associated. The blade is preferably'formed of a single piece of metal and is rigidly secured to an end portion of a long spiral stem, and since the blade is a small and in expensive article it may be economically made of a high grade material well adapted to withstand the service to which it subjected.

An important advantage in connection with my drill is that the blades, being detachable, may be removed from the stems and replaced by other blades whenever necessary, thereby eliminating the necessity of taking the drill stems from tic mines to sharpen the cutting blades as is ordinarily done. Due to the fact that the wear is on the detacha le blades and not on the drill stems, it is apparent that a single drill stem may be used for a long period of time.

Vfith the foregoing and other objects in view, the invention comprises the novel construction, combination and arrangement of parts hereinafter more specifically described and illustrated in the accompanying drawings, wherein is shown the preferred embodiment of the invention. However, it is to be understood that the invention co1nprehends changes, variations and modifications which come within the scope of the claim hereunto appended.

I is a View of the lower portion of a drill constructed in. accordance with my inrention. V

Fig. II is a view looking in the direction indicated by the feathered arrow adjacentto F l.

Ill a fragmentary vertical section showing the manner .in which the blade of my improved drill attached to the stem thereof. 1 7

1V is a View showing the lower bircated end portion of the stem of my improved drill.

Fig. V is a perspective of the blade of my improved drill.

l ig. V1 is a horizontal section on the line VI -VI of Fig. I. 1

in the drawing, A. designates a drill stem in the form of a spiral conveyor and having a lower bifurcated end portion B, the oppositely disposed legs of said bifurcated end portion B being provided with registering openings C which are intended for a pur pose to be hereinafter set forth.

The blade D of my improved drill is preferably formed of a single piece of material and is provided with a pair of cutting edges 1. Located at the upper edge of the blade D is a notch 2, and formed through saidblade at a point approximately intermediate of the upper and lower edges thereof is an opening 3, said opening 3 being approximately the same diameter as the openings G formed through the legs of the bifurcated lower end portion B of the drill stem. The blade D is provided with a flat intermediate portion D and a pair of outwardly bent wings. D at the lower edges of which the cutting edges '1 are located.

To assemble the drill'stem and the blade of my improved drill the flat intermediate portion D of the blade D is introduced between the legs of the bifurcated lower portion B of the drill stem, and said blade is .moved upwardly into the space between the legs of said bifurcated portion until the opening 3 in the blade D registers with the opening C in the legs of said bifurcated end portion B. A belt a is then passed through the registering openings G and 3 and a nut 5 is screwed on the threaded end of the bolt 4 and is caused to bear lirnily against the outer face of the adjacent leg of the bifurcated end portion B. When the drill stem and blade are assembled as described, the portion of the stem which is located at the top of the space between the legs of the bifurcated por tion B and which is designated by the reference character 6 extends into the notch 2 a the upper edge of the blade, the upwardly extending walls 2' of said notch 2 embracing said portions 6. T his arrangement will eliminate any tendency for the blade D to pivot about the single fastening device, namely, the bolt l.

In connection with the invention disclosed herein there are two extremely important features aside from the simplicity of the device, which should be noted. The first feature referred to is the Very rigid and durable structure produced at the bifurcated end of the drill stem A. It is apparent th snapped off.

the strain produced when the drill isbeing used is transferred. from the blade I) through the legs of the bifurcated end portion B of the stem to said stem. a very rigid structure must be provided at the point mentioned, otherwise the legs of said bifurcated end portion would With the foregoing in mind, I produce the stem A of my drill so that the spiral ribs A forming a part of said stem extend downwardly and form integral parts of the oppositely disposed legs of the bifurcated end portion B of the stem (Figs. I and VI). These spiral ribs function stren thening flanges which strengthen the legs of the bifurcated portion at the points where the greatest strain comes during the use of the drill and at the points where said. logs would be mostjlilzely to snap in the alisei'ice of strengthening means.

The second feature retina-ed to is the arrangement of the spiral ribs A of the stem A with relation to the cutting-blade I) of the drill. By referring-i to Fig. 11 of the drawing it will be seen that the inclined edges 1) of the wings D of the blade follow the curvature, more or less, of the spiral ribs A of the stem. In other words, spiral conveying means are provided which extend continuously from the cutting edges of the blade to the opposite end of the drill stem .A. This is important because it keeps the hole being drilled free from cirttings L/LKS there are no breaks in the conveying means where the propulsion of the cuttings arrested.

It will vbe noted that the notch 2 is pro- It is also plain thatbev vided with inclined side walls V).

The reason for this arrangement is to insure contact between the sidewalls of the notch and the portion 6 of the" associated drill stem even-through the blade- I) is used r with drill stems having portions 6 of vary ing thicknesses. To permit the blade D to move vertically when drill stems having portions 6 of varying thicknesses are used, I make the opening 3 in the blade I) elongated shown in Fig. V.

I claim: 7 p v In a boring tool, the combination with an, integrally formed single twist drill terminating in a pair of spaced, integral, oppo-.

sitely disposed ears of approz-zimately equal length, said ears being completely alined with each other transversely of the major the base of the spaced ears, and. ineansfir fastening the blade substantially midway of its longitudinal and transverse axis direct-- ly to the ears, said means being extended through and supported at its opposite ends by said spaced ears, said cutting blade being so shaped that when secured to the drill the single twist is substantially uniform througlr j out the combined lengths of the drilland the blade.

In testimony, that I claim the foregoing my signature.

I hereunto affix I SAMUEL T. SKEEN. 

